This invention pertains primarily to a method and mechanism for removing clogged waste material from the holes in tubular suction rolls utilized in the paper-making industry but the present invention is not restricted to the clearing of holes and may be used to drill initial holes in tubular members. Suction rolls used in the stated industry vary in size from the order of eight or ten feet in length up to twenty feet and, in diameters from one foot or more to as much as three feet or more. In general, the walls of the suction roll may be as much as three or more inches and, in many instances, they are formed of metal, such as brass, and the exterior surface is covered with a limited thickness of rubber-like sheeting which is ground to a uniform surface. The rolls are used to extract water from the paper webs shortly prior to the same passing to dryer units and in the operation thereof, the water withdrawn from the paper webs includes particles of filler material, such as finely ground clay and otherwise, which tends to become collected in the patterns of multitudinous holes of relatively small diameter which are formed in the drum, such as in the order of one-eighth inch or possibly slightly larger, and ultimately said holes become more or less substantially clogged with such material. A common method of freeing the holes of the material is to employ groups of servicing personnel on opposite sides of a horizontally disposed clogged roll and by the use of individual electric drills, they are individually cleared of such compacted accumulations. Obviously, such operation is very time consuming for a substantial group of employees who otherwise could be usefully employed in production operations. It is the object of the present invention to provide mechanism and a method which at most requires only two operators using drilling equipment described in detail hereinafter, for purposes of much more rapidly freeing the holes of clogged material and restoring the same to useful life.
The principal piece of equipment utilized in the present invention and method comprising a part thereof is what is commonly known as a gang drill, but one which has been especially adapted to operate efficiently and beneficially in removing accumulated matter from the multitudinous holes in such aforementioned suction rolls. Gang drills in many forms have been developed heretofore. In general, those which have been previously devised have been designed for specific purposes. For example, prior U.S. Pat. No. 1,329,663 to Hill, dated Feb. 3, 1920, in which a single row of drills are operated by common means for simultaneous rotation of all of the drills by means of elongated chains engaging sprockets on the drill shafts. Prior U.S. Pat. No. 2,357,728, to Anguera, dated Sept. 5, 1944, illustrates another row of substantially spaced drill heads designed to simultaneously drill holes in chassis for vehicles or similar objects, the drills respectively being operated by individual electric motors connected thereto by belts.
Another prior U.S. Pat. No. 3,124,977 to Obear, dated Mar. 17, 1964, illustrates a gang drill designed to drill holes in railroad rails for purposes of connecting attaching plates thereto, and in this structure a single motor, by means of a plurality of chains operates gangs of three drills simultaneously. In view of the fact that suction rolls of the type in which the present invention in applicable are cylindrical, and the holes therein are radial, it has been found that in prior U.S. Pat. No. 1,835,539 to Thomas, dated Dec. 8, 1931, a gang of radially disposed drills have been provided for simultaneously drilling radial holes in a cylindrical object.
Also, other prior patents have been developed which utilize either a single or a limited number of drill heads in connection with drilling radial holes in cylindrical objects, the following patents illustrating examples of such previously devised machines:
U.S. Pat. No. 1,399,073--Pahmeyer et al Dec. 6, 1921 PA0 U.S. Pat. No. 1,511,415--McEvoy Oct. 14, 1924 PA0 U.S. Pat. No. 1,559,359--Pahmeyer Oct. 27, 1925
Having found none of the foregoing stuctures illustrated in the various patents to be applicable to the problems solved by the present invention, what is believed to be a novel type of gang drill and method of operating the same has been devised with the following objectives in mind.